I did a quick check right now and couldn't find it either (always easy to find shipment numbers, but not user base). I am pretty sure it was an IDC or Gartner

I did a quick check right now and couldn't find it either (always easy to find shipment numbers, but not user base). I am pretty sure it was an IDC or Gartner chart that I saw that showed worldwide pc users per year. Let me do some checking this afternoon when I have more free time and will post a link.